1. Technical Field
This invention relates to a method for coating a sliding element and a sliding element, in particular a piston ring. It is a requirement for sliding elements, such as piston rings, that they only ever bring about small friction losses. For example, with piston rings acting as sliding elements in internal combustion engines, and increase in friction has a direct effect upon fuel consumption. Furthermore, oil consumption is affected by the condition of the piston rings. In particular, with regard to this, the so-called burn mark strength and outbreak strength, which must be particularly high in order to permanently realize the required friction values, are to be observed.
2. Related Art
As previously used items piston rings are known which are coated by means of PVD methods on a hard material base, in particular chromium nitride. Furthermore, the electrochemical deposition of chromium layers associated with the incorporation of Al203 or diamond particles, the size of which comes within the micrometer range, is known.
A DLC (diamond-like carbon) coating system, that can include tungsten carbide depositions in nanocrystalline form, which are produced during the separation process and are up to 10 nm in size, is revealed by WO 2007/079834 A1.
Finally, DE 199 58 473 A1 relates to a method for producing composite layers with a plasma beam source, wherein nanocrystalline particles can be embedded, and that can be combined with know, separately controllable CVD or PVD methods.